Currently, a mobile communication system means a system for providing a communication service to a user terminal (e.g. a cellphone) by an operator arranging devices such as a wireless access network device (e.g. a base station), a core network device (e.g. a home location register, HLR in short), etc. The mobile communication technique has been through the development of a first generation, a second generation, a third generation and a fourth generation. The first generation of mobile generation applies a cellular telephone standard with original analog restricted to voice call, which mainly uses an access method with simulation technology and Frequency Division Multiple Access (FDMA in short). The second generation of mobile communication introduces a digital technology, which enhances network capacity, improves voice quality and security, and is represented by Global System for Mobile Communication (GSM in short) and Code Division Multiple Access (CDMA IS-95 in short). The third generation of mobile communication applies three technologies, i.e. CDMA2000, WCDMA and TD-SCDMA, all of which use Code Division Multiple Access as an access technology. The fourth generation of mobile communication has a relatively unified standard in the world, which is Long Term Evolution/Long Term Evolution-Advanced (LTE/LTE-A in short) constituted by 3GPP of the International Standardization Organization, wherein its downlink is based on Orthogonal Frequency Division Multiple Access (OFDMA in short), and its uplink is based on an access method of Single Carrier-Frequency Division Multiple Access (SC-FDMA in short). The fourth generation of mobile communication systems achieves a high-speed transmission with a downlink peak rate of 1 Gbps and an uplink peak rate of 500 Mbps by a flexible bandwidth and a self-adaptive modulation coding manner. FIG. 1 briefly shows a basic architecture of a mobile communication network. As shown in FIG. 1, when a user terminal is connected with an access network (e.g. a base station), the access network transmits data to a core network via a backhaul link between the access network and the core network (e.g. HLR), or the core network transmits data to the user terminal (e.g. a mobile phone) via the backhaul link.
MulteFire is a newly defined uplink transmission method based on a downlink transmission method of LTE R13 LAA. This method belongs to a LTE technology independently working at an unauthorized frequency range, i.e. stand-alone LTE-U. MulteFire applies a B-IFDMA way different from a conventional LTE uplink SC-FDMA with respect to an uplink multiplexing way, in order to meet a regional regulatory requirement on a bandwidth occupancy at an unauthorized frequency range, and introduces an MulteFire extended physical uplink control channel MF-ePUCCH in an uplink physical channel PUCCH to transmit uplink control information UCI (including ACK/NACK, CSI, SR etc.) which is transmitted via PUCCH in a conventional LTE. Because of a resource allocation characteristic of B-IFDMA, its minimum resource allocation granularity is larger. As shown in FIG. 2, there are ten interlaces in a bandwidth of 20 MHz, each interlace is numerically equal to ten uniformly-spaced PRBs in a frequency domain, and No. zero is ten black PRBs. Therefore, with respect to an uplink multiplex way applying B-IFDMA in MulteFire, by using a way of allocating an uplink control channel region (PUCCH region) at each uplink subframe in a conventional LTE, the extended physical uplink control channel region (MF-ePUCCH region) occupies at least a ratio of up to 10% of the bandwidth of the system, but meanwhile the user terminal UE does not have so much UCI necessary to be transmitted.
In order to solve the above problem of large control cost resulting from the inherent existence of MF-ePUCCH at each uplink subframe, it is necessary to use a method of dynamic indication to trigger a transmission of MF-ePUCCH of UE at appointed uplink subframe. A current triggering method includes solely indicating an MF-ePUCCH location of each UE by DL/UL grant, which is similar to resource indication of PUSCH. The advantage lies in flexible indication, but the problem mainly lies in that when a large number of users need transmissions at MF-ePUCCH, UL grant leads to a large cost of downlink signaling.